Vitamin D: Blacks need much more

The sunshine vitamin offers a broad range of benefits—from boosting bone and muscle strength to offering protection against cancer and diabetes. Unfortunately, the diet is a poor source of vitamin D, and dark skin filters out much of the sun’s vitamin-producing ultraviolet light. To achieve healthy concentrations of vitamin D, therefore, many African-American women may need hefty daily supplements, a new study finds.

Researchers at the Winthrop University Hospital in Mineola, N.Y., recruited 208 postmenopausal black women for a 3-year trial during which half received large daily doses of vitamin D.

Increasingly, nutrition scientists advocate at least 75 nanomoles of vitamin D per liter of blood as a minimum target value for health, notes John F. Aloia, an endocrinologist and coauthor of the study.

Even after 2 years of supplementation with 800 international units of vitamin D daily—twice the recommended daily intake—treated women attained only 88 percent of the target value for this vitamin in their blood, Aloia’s group reports in the December American Journal of Clinical Nutrition. The supplemented women reached the target value only after their intake was bumped up to 2,000 IU per day in the third year of the trial.

Janet Raloff

Janet Raloff is the Editor, Digital of Science News Explores, a daily online magazine for middle school students. She started at Science News in 1977 as the environment and policy writer, specializing in toxicology. To her never-ending surprise, her daughter became a toxicologist.

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